Last October, the 197 signatories to the Montreal Protocol met in Kigali, Rwanda, and reached an agreement to limit the use of hydrofluorocarbons. HFCs were first introduced in the 1980s as substitutes for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) which were identified as ozone depleting chemicals (ODCs.) ODCs contain either chlorine or bromine. Fluorine, on the other hand, does not harm the ozone layer.
CFCs and HCFCs were used as refrigerants, solvents, blowing agents for plastic foam manufacture and fire extinguishers. While HFCs are not harmful to the ozone layer, they are greenhouse gases with extremely high global warming potentials (GWPs.) GWP is a measure of how much energy the emissions of a particular gas will absorb over a given period of time relative to the emissions of a similar amount of carbon dioxide. (see also my Feb. 14, 2016 blog, US is making Progress in Reducing Methane Emissions)
The Kigali Amendment caps and reduces the uses of HFCs with the United States, Europe, and Japan reducing levels by 10 % starting in 2019. Other countries including China have until 2024. Exceptions were made for India, Pakistan and some Gulf States which are allowed a later start date of 2028.
Even before the Kigali meeting in Oct. 2016, some steps were taken to phase out HFCs. In 2011, the European Commission enacted the Mobile Air Conditioning (MAC) Directive to reduce GHG emissions of air conditioning systems in passenger cars and light commercial vehicles. This required that all refrigerants sold after Jan.1, 2013 have a GWP lower than 150. The United States, Japan and other countries have also proposed or issued regulations encouraging the use of low GWP refrigerants in automotive air conditioning systems.
As a result, several fluorocarbon chemical companies including DuPont and Honeywell started looking for alternatives that would satisfy the MAC Directives. The two companies decided to combine research efforts and collaborated in developing and commercializing the technology for the production of hydrofluoroolefins (HFOs.) These are hydrogen and fluorine molecules containing at least one double bond and having very low GWPs.
One of the HFOs resulting from this collaborative effort is 2,3,3,3 tetrafluoropropene (CF3CF=CH2) known commercially as HFO-1234yf. It has a GWP of 4 and is a replacement for the HFC refrigerant, HFC 134a, (GWP = 1480) used primarily in automotive air conditioning systems.Both DuPont and Honeywell have built production plants to produce HFOs under separate brand names; Opteon™ and Solstice™ respectively. In July, 2015, DuPont spun off its performance chemicals division including all its fluoro products into a new company known as Chemours. As a result, Chemours inherited DuPont’s long and rich history in the development of fluorochemicals:
With the European Union MAC directives already in place and implementation of the Kigali amendments becoming effective in the next few years, both Honeywell and Chemours see a bright future in the demand for HFOs. Both companies have and are continuing to expand production of their individual HFO brands: Solstice tm for Honeywell, Opteontm for Chemours. Honeywell has production facilities in Geismar, La. while Chemours has fluorocarbon plants in China, Japan and the U.S.
The original Montreal Protocol, which became effective in 1987, called for developed countries to begin phasing out CFCs in 1993 with a 50% reduction goal by 1998. With the Oct. 2016 Kigali Agreement, the Protocol has been amended eight times. In 1992, the Copenhagen Amendment among other conditions added the phase out of HCFCs beginning in 2004 in developed countries. Overall the Montreal Protocol has been successful in reducing the emissions of ODCs and projections are that the ozone layer will be fully restored by the middle of this century.
The following illustration is a simplified view of the transition resulting from the Montreal Protocol and its various amendments from ozone depleting and high global warming potential CFCs to zero ozone depleting and very low GWP HFOs:
However not all may be as optimistic as it appears for large scale deployment of HFOs. In July, 2016, Greenpeace issued a position paper opposing the application of HFOs. Several reasons were cited:
- HCFCs are used to make the most prominenet HFO, HFC-1234yf
- HFO blends have high GWPs
- HFOs and other HFCs produce toxic by-products upon their production and decomposition
- Toxic flammability of HFC-1234yf in MACs
- Higher costs of HFOs
For more details regarding their opposition to HFOs click here.
Greenpeace concluded there is no need for HFOs as they do not provide long term sustainable solutions. They believe there are environmentally friendly natural occurring materials available that can and have been used as refrigerants and should be utilized in place of HFOs. Common natural refrigerants include carbon dioxide (R744), ammonia (R717), water (R718) and hydrocarbons such as propane (R290) and isobutane (R600a).
Should Greenpeace’s objections to HFOs gain support among the Montreal Protocol signatories, we may yet see sometime in the future another amendment phasing out the use of HFOs. Though it’s unlikely this would garner US support under the current administration’s disdain for additional environmental regulations and the newly confirmed head of the Environmental Protection Agency.